An aqueous suspended agricultural chemical composition is generally referred to as a flowable formulation, which is a formulation formed by suspending an agricultural chemical active ingredient in a liquid. Since the formulation uses the agricultural chemical active ingredient in a pulverized form, it can prevent the agricultural chemical active ingredient from being separated, precipitated, redispersed, or the like by the addition of supplementary agents such as a surfactant and a thickening agent. Micropulverization of the agricultural chemical active ingredient is an important method for improving the dispersion stability thereof in the liquid and enhancing biological effects (effects on pest control).
However, such micropulverization of the agricultural chemical active ingredient causes crystal growth of the ingredient due to Ostwald ripening during storage, namely the particle size of the ingredient tends to be increased, which not only adversely affects the quality of the formulation due to separation, precipitation, and caking and the like, but also decreases the biological effect. Thus, there is a great need to solve such problems from a practical viewpoint.
In order to solve the problems, there have been many approaches in the past to suppress the crystal growth of the agricultural chemical active ingredient and physically stabilize the formulation.
For example, Japanese Patent Application Laid-Open Publication No. 208404/1997 (Patent Document 1) discloses a suspension composition comprising an agricultural chemical active ingredient in combination with ingredients such as a polycyclic aromatic nonionic/anionic surfactant, which is stated to have good storage stability. Also, Japanese Patent Application Laid-Open Publication No. 532395/2002 (Patent Document 2) discloses that a triazole fungicide can be used with a combination of a surfactant such as tristyrylphenol-ethoxylate or a sulfate thereof and a polymer such as a vinylpyrrolidone homopolymer for the purpose of preventing crystal growth. Furthermore, Japanese Patent Application Laid-Open Publication No. 163401/2010 (Patent Document 3) discloses a composition containing crystalline cellulose, urea, a surfactant and the like in order to suppress the particle growth of the agricultural chemical active compound. However, there were some cases where the above-mentioned surfactants were not suitable for practical use because the surfactants may sometime function in an opposite manner and accelerate the crystal growth instead.
Furthermore, Japanese Patent Application Laid-Open Publication No. 175904/1997 (Patent Document 4) discloses coating of an agricultural chemical active ingredient with a resin compound in order to prevent the particle from being grown or becoming coarse during storage. However, there were some cases where it was difficult to maintain the storage stability because the particle size became large due to the coating of the particle.
Furthermore, Japanese Patent Application Laid-Open Publication No. 16741/2011 (Patent Document 5) discloses an aqueous suspended agricultural chemical composition comprising an agricultural chemical active ingredient in combination with a resin, a sulfonate condensate, and a surfactant. However, there were some cases in the past where the particle growth could not be sufficiently suppressed depending on the type of the agricultural chemical contained in the aqueous suspended agricultural chemical composition.
Furthermore, Japanese Patent Application Laid-Open Publication No. 79741/2011 (Patent Document 6) discloses an agricultural chemical composition which exerts the effect of the agricultural chemical active compound by being spread over a whole rice paddy after first by being brought into contact with leaf surfaces of a crop. However, it has been known that, under some particular storage conditions, the particles of the agricultural chemical active ingredient may grow and become coarse particles; and in fact, there were some cases where the nozzle of the spray was clogged by the agricultural chemical active ingredient when spraying, and the composition could not be practically used as a product. In addition, even if the agricultural chemical active ingredient could be sprayed out, its biological effect (effect on pest control) would be significantly decreased because the particles of the agricultural chemical active ingredient have become coarse.
Therefore, it has been desired to provide a formulation in which the particle growth of the agricultural chemical active ingredient is suppressed for a long time under various storage conditions.